We propose to leverage the power of the Internet and the appeal of on-line gaming environments for middle school students to create a new type of learning resource in science. Case histories of medical discovery will be transformed into "problem- based" multimedia mysteries for students to solve. Through prior research we have developed and field tested a working model for an adventure series that engages middle school students. We propose to extend the model to new content. Assuming the on-line role of a Reconstructor who seeks lost medical knowledge from the past, students will unravel the origins of specific diseases or medical discoveries. The learning objectives for each episode will be multidisciplinary. The goal is to engage students in constructing their own knowledge by participating in virtual experiments, by helping them establish a context for the discoveries, and by understanding issues involved in forming public health policy. An experienced team representing medicine, biology, history of science, education, and information technology will oversee the project, assuring the integrity of the site content, and incorporating cutting edge technology. A process of iterative prototyping, focusing heavily on teachers and students will be employed to make the resource site exciting, educational, and useful in classrooms, in homes, and in museums. The field tests will be conducted in schools, representing a cross-section of the community, assuring appropriate presentation of materials to target populations.